Telephone receiving-instrument



(No Model.) R DUNGER TELEPHONE RECEIVING INSTRUMENT.

'Patented Aug. 27, 1889.

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UNITED STATES PATENT OFFICE".

ROBERT DUNGER, OF CHICAGO, ILLINOIS.

TELEPHONE RECEIVING-INSTRUMENT.

SPECIFICATION forming part of Letters Patent No. 409,736, dated August 27, 1889.

Application led January 15, 1889. Serial No. 296,442. (No model.)

To @ZZ whom, it may concern:

Be it known that I, ROBERT DUNGER, of Chicago, Illinois, have invented certain new and useful Improvements in Telephone Receiving-Instruments, of which the following is a speeilieation;

My invention relates to the construct-ion of a diaphragm and magnet of a receiving-im strument.

In the accompanying drawings, Figure l is a longitudinal section, and Fig. 2 a cross-section on line 2 2 of Fig. l, of an instrument Containing my invention.

A is a ease of substantially the ordinary form.

B is the coil or helix.

C are the binding-posts for connecting the instrument to line-Wires.

D is the bar or magnet upon the end of which the eoil B is placed.

In the instrument shown in the drawings the bar D is made of three pieees, the outer ones E being of hardened steel and the inner one F of soft steel or soft iron. This softiron central piece is longer than the others, and its end is drawn out, as at G, to a size and form sufficient to extend from the back end of the bar forward through the case to the front again, Where it is flattened so as to form thel diaphragm I. At H this return-pieceis corrugated, as shown in Fig. l, so as to permit the adjustment of the diaphragm and magnet with reference to each other Without straining any of the parts. To the back end of the bar is secured a button J, of brass or other suitable material, to receive the screw K by which the adj ustment is effected.

By this construct-ion the diaphragm forms one pole ot the magnet., the other pole being the end of the bar adjacent to the diaphrag m I claiml. In a telephone-receiver,a magnet having the coil upon one end and having its other end flattened to form the diaphragn'l, With the corrugated portion II, substantially as set forth.

2. In a telephone, the combination of the hardened-steel portions E, the soft-metal poi'- tion F, the return-bar G, having its end flattened into the diaphragm I, and the corrugated portion I'I, substantially as set forth.

ROBERT DUNGER.

Titnessesz WM. S. BATES, ANDREW J. EGHERT. 

